1. Field of the Invention
The present invention relates to a method of monitoring the sound within a car, and more particularly, to a method of monitoring the sound within a car at a place remote from the car by utilizing a mobile telephone system.
2. Description of the Prior Art
Anti-theft devices which prevent auto theft are conventionally known. When a thief attempts to steal a car incorporating such an anti-theft system by opening a door of the car, applying considerable force to the car, or opening the trunk, the anti-theft system is actuated to cause a siren to blow or the headlamps to be turned on and off, thereby obstructing the attempted theft.
However, the alarm sounded by the siren or flashing of the headlamps is only effective if there are people nearby, and does not exhibit sufficient deterrent in deserted locations or at night. Therefore the applicant of the present invention has proposed a method of reporting the occurrence of abnormality to the driver by transmitting that fact to a remote control unit, which thereby sounds an alarm.
Even when the car is not actually being stolen, the remote control unit sometimes sounds the alarm because the shock sensor is actuated by force applied from the outside, because a noise sensor is actuated by excessive external noise, or for other reasons. On the other hand, when the car is actually being stolen, it is sometimes dangerous for the owner to run to the car alone. In such a case, the owner will want to ascertain the state of the anti-theft system before running to the car when he receives the alarm from the remote control unit, but no method of ascertaining the state of the car secretly at a place remote from the car has heretofore been known.